1. Field of the Invention
The present invention relates generally to controlling valves for modules of semiconductor processing equipment, and more particularly to controlling the operation of dual sided slot valves and methods of implementing operations of such valves between separate chambers of semiconductor processing equipment so that processing operations may continue in one chamber during servicing of the other chamber.
2. Description of the Related Art
In the manufacture of semiconductor devices, process chambers are interfaced to permit transfer of wafers, for example, between the interfaced chambers. Such transfer is via transport modules that move the wafers, for example, through slots or ports that are provided in the adjacent walls of the interfaced chambers. For example, transport modules are generally used in conjunction with a variety of substrate processing modules, which may include semiconductor etching systems, material deposition systems, and flat panel display etching systems. Due to the growing demands for cleanliness and high processing precision, there has been a growing need to reduce the amount of human interaction during and between processing steps. This need has been partially met with the implementation of transport modules which operate as an intermediate handling apparatus (typically maintained at a reduced pressure, e.g., vacuum conditions). By way of example, a transport module may be physically located between one or more clean room storage facilities where substrates are stored, and multiple substrate processing modules where the substrates are actually processed, e.g., etched or have deposition performed thereon. In this manner, when a substrate is required for processing, a robot arm located within the transport module may be employed to retrieve a selected substrate from storage and place it into one of the multiple process modules.
As is well known to those skilled in the art, the arrangement of transport modules to "transport" substrates among multiple storage facilities and process modules is frequently referred to as a "cluster tool architecture" system. FIG. 1 depicts a typical semiconductor process cluster architecture 100 illustrating the various chambers that interface with a transport module 106. Transport module 106 is shown coupled to three process modules 108a-108c which may be individually optimized to perform various fabrication processes. By way of example, process modules 108a-108c may be implemented to perform transformer coupled plasma (TCP) substrate etching, layer depositions, and/or sputtering.
Connected to transport module 106 is a load lock 104 that may be implemented to introduce substrates into transport module 106. Load lock 104 may be coupled to a clean room 102 where substrates are stored. In addition to being a retrieving and serving mechanism, load lock 104 also serves as a pressure-varying interface between transport module 106 and clean room 102. Therefore, transport module 106 may be kept at a constant pressure (e.g., vacuum), while clean room 102 is kept at atmospheric pressure. To prevent leaks between modules during pressure varying transitions, or to seal off a process module from transport module 106 during processing, various types of gate drive valves are used to isolate the various modules.
For more information on gate drive valves, reference may be made to U.S. Pat. No. 4,721,282, which is hereby incorporated by reference. Another such gate drive valve is shown in U.S. Pat. No. 5,667,197, in which a prior art valve housing is shown having two port openings, and only one valve for one of the two port openings. Thus, it is not possible to close each of the two ports at the same time, nor to close only the port that does not have an associated valve. Also, the gate plate valve of the '282 Patent is shown for closing a port between abutting transport and process chambers, and no intermediate valve housing is provided. A drive assembly for the gate plate moves the gate plate in one continuous motion in a vertical path and in a rotating arc toward the internal port to effect a seal or closure of the internal port.
Additionally, operation of a drive assembly for the gate drive valve is monitored by a series of sensors that provide signals to a monitoring computer. However, the primary function of the computer is to analyze the movements of the drive assembly relative to the movements of a robot arm. Thus, the computer does not control the drive assembly to coordinate operation of the gate valve relative to multiple states of operation of process modules, for example.
U.S. Pat. No. 5,150,882 shows one valve between various chambers of a treatment system, including between a decompression chamber and an etching chamber. Such one valve is driven for engagement and disengagement with a gate aperture by one air cylinder and a toggle arrangement such that stopper plates hit rollers with considerable impact. Initial vertical movement of a fitting plate is changed to horizontal movement by the link that is rotated counterclockwise, such that the gate moves toward the gate aperture. For the '882 Patent to avoid problems of the prior art, the stopper plates are made from a double boride hard alloy. Further, the single motion of the one air cylinder is not stopped, but instead continues its driving operation after the abutment of the stopper plates with the rollers. Thus, in addition to requiring special materials, the '882 Patent does not provide two valves between adjacent processing chambers. Additionally, the '882 Patent does not describe a system for coordinating operation of the one air cylinder with respect to multiple states of operation of process modules. U.S. Pat. No. 4,753,417 shows a gate valve having a pair of wheels and a linear actuator for operating the valve. To facilitate process control the gate valve is fitted with sensors such as micro switches that sense gate valve positions. However, the '417 Patent also does not describe a system for coordinating operation of the linear actuator with respect to multiple states of operation of process modules.
In view of the forgoing, what is needed is a valve assembly between adjacent processing or transport chambers, and a control system for operating the valve assembly to assure that operations in one such chamber may continue while the other chamber is in one of multiple states of operation.